I'm really struggling with my breathing the last couple of days. It feels heavy and I'm breathing super fast, plus I'm yawning all the time. My heart's been racing too, and it's making me so anxious. My nose is clear and my hemoglobin's normal, so I'm at a loss about what's going on. I'm constantly worrying about my breathing now and focusing on it just seems to make it worse. Any idea what this could be? It's really stressing me out.